Here is my method and link to the YouTube video that inspired it…
Apply strips of tape over each group of 4 lines and rub thoroughly over them with a plastic card.
Trim off excess paper around the text and trim the tape length.
Soak the paper for a minute or so.
Rub off the paper from each strip of tape.
Dry the tape on paper towels sticky side up, carefully allowing to dry, the glue will restore itself completely.
Stick them onto your postcard and viola.
I got this from this cool YouTube video…